In patients experiencing cardiopulmonary failure, a need exists to perfuse blood systemically. A femoral arterial cannula is typically used to infuse oxygenated blood into the body at the groin. To supply an adequate amount of oxygenated blood, the outer diameter of the cannula often occludes the inner diameter of the blood vessel as oxygenated blood is delivered through the lumen within the cannula. Blood exits the cannula from an opening at the distal end which typically directs blood toward the heart of the patient. For patients undergoing long-term cardiopulmonary assistance, the problem of ischemia in the lower extremity arises since the cannula blocks blood flow to the lower leg. A need exists to supply adequate blood flow to the lower leg tissues.
Prior attempts to obviate ischemia caused by arterial cannula occlusion have been awkward and inadequate. For example, the insertion of an arterial cannula in the aorta to avoid blockage has been suggested. Admittedly, the large diameter of the aorta permits the insertion of a large cannula without resulting in distal occlusion. However, such abdominal or thoracic surgery is invasive and more dangerous than the insertion of a cannula in a femoral artery. These dangers limit invasive techniques to only the most critically ill patients.
A second cannula can also be used to deliver blood to the lower leg when the femoral artery has been occluded by the systemic cannula. For example, a Y connector and tube could be inserted proximal to the occluding cannula and the distal end of the tube fitted with a catheter which is inserted into the femoral artery distal to the cannula. This also requires extra hardware and another cannulation.